When a plurality of power semiconductor switching devices are connected in parallel, a closed circuit is formed by respective gate to drain (or gate to source) capacitances of the semiconductor elements and a wiring inductance. In this closed circuit, parasitic oscillation may occur during turn-on or turn-off of the semiconductor switching devices (parasitic oscillation is likely to occur particularly during turn-off of the semiconductor switching devices). Occurrence of parasitic oscillation may cause breakage of the semiconductor switching devices. This parasitic oscillation is a problem peculiar to the configuration where a plurality of semiconductor switching devices are connected in parallel.
In order to avoid this problem, generally a gate resistor having a relatively large resistance value is connected to the gate of each semiconductor switching device. For example, according to Patent Document 1 (Japanese Patent Laying-Open No. 2003-088098), parasitic oscillation is suppressed by a damping resistor on the output terminal side of a gate drive circuit.